Jan Willem Sjoerdsma, born in Dokkum on April 24, 1879.

Jan was married to
Barnadina Bons, born in Ooststellingwerf on April 23, 1881.

• 1 : Sietske Sjoerdsma, born in Leeuwarden on November 29, 1903, died in Harlingen on August 29, 1979, buried there, aged 75 years.
  Sietske was married in Harlingen on December 29, 1924, at the age of 21 to Gerrit Tigchelaar (aged 25 years), born in Harlingen on September 23, 1899, son of Roelof Gerrits Tigchelaar (potatodealer, workman, shopkeeper, bargeman, worker, workman and earthenware baker) and Gerritje Elisabeth Koster, bargeman, docker and fuel dealer, died in Harlingen on October 1, 1954, buried there in October 1954, aged 55 years.